1. Technical Field
The disclosure relates to light emitting diodes, and particularly to an LED epitaxial structure and a method for manufacturing the LED epitaxial structure.
2. Description of the Related Art
Light emitting diodes' (LEDs) many advantages, such as high luminosity, low operational voltage, low power consumption, compatibility with integrated circuits, easy driving, long term reliability, and environmental friendliness have promoted their wide use as a light source. Now, light emitting diodes are commonly applied in environmental lighting. However, a common LED structure is epitaxial grown on a sapphire. A large difference of lattice constant and thermal expansion coefficient is between an epitaxial layer and the sapphire. That produces high density dislocation. Furthermore, high density dislocation reduces the light emitting efficiency. Therefore, the epitaxial layer will absorb part of the light from an active layer. A part of light from the active layer is confined due to high refraction efficiency and is absorbed by the substrate. Therefore, increasing light extraction efficiency is an important issue.
Therefore, it is desirable to provide an LED epitaxial structure and a method for manufacturing the LED epitaxial structure, which can overcome the described limitations.